text ematch: check for NULL pointer before destroying textsearch config

text ematch: check for NULL pointer before destroying textsearch config

While validating the configuration em_ops is already set, thus the
individual destroy functions are called, but the ematch data has
not been allocated and associated with the ematch yet.

Signed-off-by: Thomas Graf <tgraf@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>